Rotary fluid flow machine



Feb. 28, 1967 H. BACHL ROTARY FLUID FLOW MACHINE 2 Sheets-Sheet 1 Filed April 15, 1965 Feb. 28, 1967 H. BACHL 3,306,574

ROTARY FLUID FLOW MACHINE.

Filed April 15, 1965 2 Sheets-Sheet 2 FIG.7

United States Patent Office Patented Feb. 28, 1967 3,306,574 ROTARY FLUID FLOW MACHINE Herbert Bachl, Turkenrtrasse 40, Munich, Germany Filed Apr. 15, 1965, Ser. No. 448,389 Claims priority, application Germany, Apr. 15, 1964, B 76,342 3 Claims. (Cl. 25339.15)

My invention relates to fluid flow machines. More particularly, it relates to such improved machine for expanding or compressing gaseous materials, mixtures of gaseous and liquid materials and mixtures of gases .and liquid materials having finely dispersed solid particles therein.

In known rotary machines which are capable of being utilized both for compression and expansion functions, an effective arrangement has been to employ part of the energy produced in expansion in an axial course of flow of working medium for compression of working medium in a radial course of flow. In this situation, the difference energy is transmitted over the shaft.

In such machines, the rotor blades may be made hollow so that a second working medium such as a cooling fluid may be caused to flow radially therethrough.

Such known machines have presented the disadvantage of having intersecting axial and radial flow paths which do not permit of design thereof to produce optimal flow characteristics. This is because in designing the cross section of these flow paths, there must be taken into consideration, the space required for the second working medium, i.e. the cooling fluid. In addition, it has been found difficult to combine compression and expansion actions for the same working medium in a single thermodynamic process, since the axial flow occurs at a given velocity with high capacity coeflicients and low pressure coeflicients but radial flow takes place at the aforesaid given velocity with lower capacity coefiicients and higher pressure coeflicients.

In my copending application Serial No. 227,477, filed October 1, 1962, now Patent No. 3,226,085, dated December 28, 1965, there is disclosed an arrangement in a rotary turbine which overcomes the disadvantages of less than optimal flow characteristics in known machines. In this application, radial flow paths of working medium are developed in the center region of the rotor wheel, substantially tangential flow paths are produced in the peripheral zone of the rotor wheel, and axial flow paths are also produced in the center zone.

It is an object of this invention to provide a fluid flow machine wherein a first working medium can be expanded in a first system of fluid flow paths and wherein a second or the first working medium can be compressed in a second system of fluid flow paths, the two path systems being uninterconnected so as not to influence each other whereby optimal results as to expansion and compression may be attained.

Generally speaking and in accordance with the invention, there is provided in a fluid flow machine for handling at least one working medium fluid and comprising rotor wheel stages mounted on an axially centrally disposed shaft therein and wherein working medium fluid is caused to flow in a substantially axial direction in the center Zone and substantially tangentially at the outer peripheries of the rotor stages; the improvement which comprises a centripetal axial flow path system and a centrifugal radial flow path system in at least one of the rotor wheel stages. These flow path systems are uninterconnected and intersect in the center zone of the aforesaid one rotor wheel stage, the working medium fluids flowing through the centripetal flow path system axially in the same direction and through the centrifugal flow path system radially in opposite directions. Thus, in the centripetal flow path system, there is effected a working medium fluid expanvelocity into pressure.

sion and in the centrifugal flow path system there is effected .a working medium fluid compression.

The foregoing and more specific objects. and features of my invention will be apparent from and will be mentioned in the following description of a fluid flow machine according to the invention shown by way of example in the accompanying drawing in which FIG. 1 is a front elevational view of a rotor wheel stage in a fluid flow machine in which axial flow of working medium fluid occurs in the center zone and tangential fluid flow takes place in the rotor wheel stage peripheral zone, FIG. 2 is a schematic section which includes the rotor wheel stage shown in FIG. 1, the section being generally parallel to the rotor axis but along some of the curved flow channels and hence not planar; FIGS. 3 and 5 show in end elevation rotor wheel stages for providing flow path systems in accordance with the principles of the invention, FIG. 4 is a schematic depiction of the flow path principles of the invention, and FIG. 6 is a schematic diagram of a gas turbine system application of the invention; FIG. 7 shows more in detail a partial section of a machine according to the invention, FIG. 8 is a cross section. along the line VIII-VIII in FIG. 7, and FIG. 9 shows part of a section along the line IXIX in FIG. 8. I

Referring now to the drawing, in FIGS. 1 and 2 there is shown a rotor 23 and a guide wheel stage. The rotor is mounted on an axially disposed shaft 21 in a fluid flow machine as disclosed in the aforesaid application 227,477, in end and side elevations respectively. Thestator 22, which comprises the guide stage, has a cap-shaped portion 22' extending over the rotor 23. It is of course realized that in such machine, required like guide elements are provided in the front and back of the rotor wheel (which are omitted for convenience of depletion and explanation), for the conversion of pressure to velocity and The operation of these machines is characterized by the fact that the flow paths,'terminating in the peripheral zone of the rotor wheel along tangentially disposed blades, include radial channels in the rotor wheel where the accumulation of working medium is divided. Thus, FIG. 1 shows an arrangement and an effect which is present in known axial-flow type turbines and which comprises hook-shaped blades in axial section. I

In accordance with the invention, the arrangement shown in FIGS. 1 and 2 is modified such that the radial portion of the flow path is obliquely disposed in axial section. In other words, the radial portion of the flow path is developed at least in a zone of intersection with an axial flow path component. Thus, in accordance with the invention, in at least one rotor wheel and guide wheel stage at least two, non-interconnected systems of flow paths are provided. In one of the systems, a first working medium is expanded and in the other of the systems of flow paths, a second or the first working medium is compressed.

Thus, as shown in the axial elevational depiction of FIG. 3, AA is the designation of the expansion channels and BB is the designation of the compression channels. The designation a denotes the entry into the expansion channels and the designation b denotes the entry into the compression channels. The working medium flows through channels AA centripetally and through channels BB centrifu-gally.

As shown in the side elevational depictions in FIGS. 4 and 5, the radial channels suitably terminate in tangential disposition at the peripheral zone of the rotor wheel although such terminations may also be cylindrical or conical surfaces. Both working media move axially in the same direction but radially in opposite directions whereby there is enabled the obtaining of optimum design conditions for the two changes of state, i.e., expansion and compression, at the same speed.

As shown in FIGS. 4 and 5, the working medium accumulation which is divided in the radial channels of the rotor wheel in one system of fiow paths can be utilized for the overlapping of the channels of the second system of flow paths and thus each flow path can be developed to provide optimum performance with the two systems affecting each other relative to space requirements only very slightly.

Thus, as compared to known fluid flow machines which provide both expansion and compression actions, the machine constructed in accordance with the principles of the invention, enables the providing of axial and radial flow paths which are mutually substantially independent, i.e., there is little, if any, mutual influencing of each other With respect to shape and required space, whereby substantially optimal performance with regard to expansion and compression may be effected. The inventive machine also makes possible such coordination of the two changes of state, i.e., compression and expansion, relative to flow and pressure coeflicients whereby substantially the same quantities of the same working medium can be used in the same thermodynamic process. To effect further equalization, it is merely necessary to arrange successively occurring pure compression or pure expansion stages.

In FIG. 6 wherein there is schematically depicted an application of a machine constructed in accordance with the principles of the invention for a gas turbine system, the designating numeral 1 denotes fuel injection, fuel being injected into a combustion chamber 2. From combustion chamber 2, the hot combustion gases produced therein are fed to the expansion channels of the machine 5, such feeding being designated by the numeral 3. Air is fed into machine 5, such feeding being designated by the numeral 4. The air fed to machine 5 is heated therein, partially by the compression process and partially by inner regenerative preheating. If desired, machine 5 can comprise a plurality of pure compression stages and the heated air may be brought to a necessary pressure therein. The heated air at the proper pressure enters and then leaves an external regenerative preheater 7, such entering being designated by the numeral 6 and such leaving being designated by the numeral 8, to enter combustion chamber 2. The expanded gas leaves machine 5 as designated by the numeral 9 and leaves preheater 7 as designated by the numeral 10.

Within the contemplation of the invention, the wall thicknesses between the flow paths are chosen such that they have both sufiicient mechanical strength for the transmission of the differential energy (expansion energy minus compression energy) to the shaft and for an intensive heat transfer from channels wherein a working medium fluid is expanded at a high temperature 'level to channels wherein compression takes place at a low temperature level.

FIGS. 7, 8 and 9 show an embodiment of a fluid flow machine according to the invention more in detail, FIG. 7 being an axial section, FIG. 8 a top view onto a rotor Wheel with a sectional illustration of the stationary guiding structure, and FIG. 9 a cross section of the rotor wheel. The flow paths are schematically entered. The flow cross sections are shown to be substantially equal, whereas in reality they are narrower in the regions of higher pressures than in the regions of lower pressures.

FIG. 7 shows at 21 a portion of the rotor shaft. The housing 22 of the machine comprises the stationary guideblade structures. Only one stage 23 of the rotor is shown in full axial width, the next following stage 24 of the rotor being partly broken away. The various seals between rotor and housing are denoted by 25.

, The working medium to be expanded enters at 26 as indicated by an arrow. The working medium to be compressed enters in the same direction at 27 in the vicinity of the rotor shaft 21. As the two media pass through the machine on respective mutually independent flowpath systems extending crosswise to each other, the machine performs work by expansion and pressure reduction of one flowing medium while simultaneously compressing the other medium. This is of practical importance particularly in gas turbine or hot-air turbine systems in which air or another suitable gas is inducted and compressed, then heated to high temperature in a subsequent stage, and subsequently again expanded to lower pressure. In a hot-air turbine the compressed air or other suitable gas is only heated. However, the heating stage may also be designed as a firing chamber in which a suitable fuei is burned, the air or other oxygen-supplying gas required for the combustion being previously compressed. The pressure conduit 26 (FIG. 7) serves to supply the gases to be expanded and consequently has a relatively small cross section in comparison with the suction duct 27 whose cross section is considerably larger.

The medium to be reduced in pressure for performing work, passes first through a nozzle group 31 in the machine housing 22. This nozzle group forms part of the guiding structure. At 42 the medium enters into the flow channel 33 of the first rotor wheel 23. Guide blades 43 are provided at the inlet of the rotor flow channel 33. In channel 33 there occurs a reversal in flow direction so that the flow passes tangentially from the rotor channel 34 into a stationary channel 35 of the housing structure 22. The working medium now passes through the direction reversing channel 36 and leaves the stationary structure through a nozzle group 37 which forms part of the second rotor-wheel stage. The working medium now passes between a set of guiding blades 44 and thence through the flow channels of the second rotor wheel, and so forth. The transitions between the stationary guiding structure and the rotating wheels likewise extend in substantially tangential directions.

The flow of the working medium to be compressed extends along analogous paths. After the medium enters into the housing at 27, it passes at 42 into the direction reversing channel 43 of the first rotor wheel 23. The medium then leaves the blades of the rotor wheel 23 at 54 and enters at 55 into the first stationary guide wheel structure of the housing 22. The direction reversing channel 46 of the first guiding stage terminates at 47 where the working medium passes into the flow channel 48 of the second rotor wheel 24.

In the illustrated embodiment the inner channel ports are located in the vicinity of the axis of rotation. If desired, however, the reversal-s in flow direction may all be located in the outer region of the rotor wheels'so that the inner peripheral speed considerably contributes to the energy conversion. In this case it is sometimes preferable to have the inner channel ports also terminate laterally in axial blades as is the case in the illustrated embodiments for the outer channel ports.

It will be obvious to those skilled in the art upon examining this disclosure that fluid flow machines according to my invention permit of a great variety of modifications and hence can be given embodiments other than those particularly illustrated and described herein without departing from the essential features of my invention and within the scope of the claims annexed hereto.

I claim:

1. In a fluid fiow machine for handling at least one working medium fluid and comprising rotor wheel and guide stages mounted on a rotatable axially centrally disposed shaft therein and wherein working medium fluid is caused to flow in a substantially axial direction in the center zone and substantially tangentially at the outer peripheries of said rotor stages; the improvement which comprises a centripetal axial flow path system and a centrifugal radial flow path system in at least one of said rotor wheel stages, said flow path systems being uninterconnected and intersecting in the center zone of said one rotor wheel stage, said working medium fluids flowing through said centripetal flow path system axially in the same direction and through said centrifugal flow path system radially in opposite directions whereby in said centripetal flow path system there is effected a working medium fluid expansion and whereby in said centrifugal flow path system there is effected a working medium fluid compression.

2. In a fluid flow machine as defined in claim 1, said rotor wheel and guide stages comprising channels which terminate in surfaces which are cylindrical to the axis of rotation.

3. A fluid flow machine as define-d in claim 1, wherein the wall thicknesses between flow paths are chosen both to have sufiicient mechanical strength for the transmission of the differential energy resulting from the subtraction of compression energy from expansion energy to said shaft and for an intensive heat transfer from channels where a working medium is expanded at a high temperature level to channels wherein a compression takes place at a low temperature level.

References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCES German printed application 15,952, Nov. 8, 1956.

MARTIN P. SCHWADRON, Primary Examiner.

E. A. POWELL, Assistant Examiner. 

1. IN A FLUID FLOW MACHINE FOR HANDLING AT LEAST ONE WORKING MEDIUM FLUID AND COMPRISING ROTOR WHEEL AND GUIDE STAGES MOUNTED ON A ROTATABLE AXIALLY CENTRALLY DISPOSED SHAFT THEREIN AND WHEREIN WORKING MEDIUM FLUID IS CAUSED TO FLOW IN A SUBSTANTIALLY AXIAL DIRECTION IN THE CENTER ZONE AND SUBSTANTIALLY TANGENTIALLY AT THE OUTER PERIPHERIES OF SAID ROTOR STAGES; THE IMPROVEMENT WHICH COMPRISES A CENTRIPETAL AXIAL FLOW PATH SYSTEM AND A CENTRIFUGAL RADIAL FLOW PATH SYSTEM IN AT LEAST ONE OF SAID ROTOR WHEEL STAGES, SAID FLOW PATH SYSTEMS BEING UNINTERCONNECTED AND INTERSECTING IN THE CENTER ZONE OF SAID ONE ROTOR WHEEL STAGE, SAID WORKING MEDIUM FLUIDS FLOWING THROUGH SAID CENTRIPETAL FLOW PATH SYSTEM AXIALLY IN THE SAME DIRECTION AND THROUGH SAID CENTRIFUGAL FLOW PATH SYSTEM RADIALLY IN OPPOSITE DIRECTIONS WHEREBY IN SAID CENTRIPETAL FLOW PATH SYSTEM THERE IS EFFECTED A WORKING MEDIUM FLUID EXPANSION AND WHEREBY IN SAID CENTRIFUGAL FLOW PATH SYSTEM THERE IS EFFECTED A WORKING MEDIUM FLUID COMPRESSION. 